Feedeeic schaepf



(No Model.)

P. SGHARPP.

INSTRUMENT FOR THE FOCAL MEASUREMENT OF OPTICAL LENSES.

No. 327,602. Patented Oct. 6, 1885.

u. PETERS, PhukrLllflogrzplwr. Washington, 11c

TATES PATENT Orrrorr.

UniTie FREDERIC SGHARPF, OF ROCHESTER, NEll YORK, ASSIGNOR TO CHARLES F.YOUNG, OF SAME PLACE,

INSTRUMENT FOR THE FOCAL MEASUREMENT OF OPTICAL LENSES.

SPECIFIGATEQN forming part of Letters Patent No. 327,602, dated October6, 1885.

Application filed June 12, 1585. Serial No. 168,454. (No model.)

1' aZZ whom, it may concern: mirrors, parts being broken away and otherBe it known that I, FnEDERIo SOHARPF, parts shown in various positionsof adjustof Rochester, in the county of Monroe and ment by full anddotted lines, parts of the de- State of New York, have invented a newand vice being wholly omitted; Fig. 3, an end useful Improvement inInstruments for the elevation of the same viewed as indicated by 55Focal Measurement of Optical Lenses, which arrow 2" in Fig. 2, drawnmore particularly improvement is fully set forth in the followto showthe orifice through which the light ing specification and shown in theaccompapasses and the horizontal wire crossing the nying drawings. same;Fig. 4, a cross-section of the cross-wire The object of my presentinvention is to box, taken on the dotted line y in Fig. 2 and 60 producean instrument for the focal measureviewed as indicated by arrow a drawnto ment of eyeglasses and other optical lenses, show more fully thecross-wire and manner of and it is designed to be animprovement uponholding the same, the orifice at the outer end my previoussimilarinventions shownin Patof the box appearing in Fig. 3 being shownin ents Nos. 196,028 and 236,911, of dates, redotted circles; Fig. 5,-asimilarviewofthe de- 6 speetively, October 9, 1877, and June 25, 1881.vice, beinga cross-section of the box, taken on The improvement consistsin making the the dotted line 1 in Fig. 2, drawn to show focusing-lensadjustable, in mounting the obthe lens and slide holding the same andthe jeet so that it maybe adjusted longitudinally, manner in which saidslide and lens are dein forming the side of the scale-box through signedto be moved laterally along ways pro 0 which the handle for the slideextends in vided therefor, said slide and lens and the rod such a mannerthat side light is excluded, in or handle connected therewith beingshown in placing over the scale a mirror so inclined as two positions byfull and dotted lines; Fig. 6, to clearly show to the operator saidscale, an aview of the end of the scale-box, seen as in- 2 index, and informing the instrument with dicatcd by arrow .2 in Fig. 2, the baseboard5 other improved parts and devices, all hereinof the device beingtransversely sectioned, below fully described, and more particularly ason the dotted line y, the figure being pointed out in the claims. drawnto show the screen for cutting off the Referring to the drawings, Figurelis a plan light and the position occupied by the lens 0 of my improvedinstrument for the focal being measured; Fig. 7, a similar view of the80 measurement of optical lenses showing the Scale-box with the lens tobe measured and cover thrown back, the box holding the cross the screenfor the light omitted,drawn to show wire and other parts beinghorizontally see the lens-tube with its contained lens; and Fig. tioned,as on the broken dotted line y in Fig. 8 a transverse section of thescale-box, taken 2, and viewed as indicated by arrow 2 in said on thedotted line if in Fig. 2 and viewed as 8 figure, a part at the adjacentend of the scaleindicated by the arrow a drawn to show the box beinghorizontally andcentrallysectioned slide carrying the mirror,image-glass, and to show the lens-tube, and a part of the scale benthandle connected with the slide and being broken away to uncover theslide, the reaching outside of the box, a portion of the latter beingshown in full and dotted line poground object-glass being broken away tounsitions, parts not essential to the figure being cover the mirror.omitted; Fig. 2, a side elevation of the in- Referring to the parts, Ais the base-board strument, showing the cover as being inclined or baseof the instrument; B, the box conat an angle of about forty-five degreesto the taining the cross-wire or object a, with other plane of thescale, the crosswire box, a part parts; 0, the box for holding the scaleF and of the scale-box, the slide, lenstube, and slide L, said boxes Band 0 being mounted other parts being centrally and vertically secuponthe base A, in line and secured rigidly tioned, as on the dotted line yin Fig. 1, and thereto, there being a space, R, left between viewed, asindicated by arrow 2', drawn to them.

50 show the relative position of the lenses and D is the cover of thescale-box, attached to I00 the latter by ordinary hinges so as to betilted thereon, the inner face of the cover being provided with amirror, K.

L is a slide placed within the scale-box and fitted to be movedlongitudinally therein under the scale, said slidebeing provided with abent handle, f, reaching to a point outside the box.

9 is a lens-tube inserted horizontally in an orifice, h, formed in theend 0 of the scale-box next the object-box B, said tube containing alens-slide, a, and traverse-screw h, for longitudinally adjusting saidlens-slide within the tube.

k is a circular opening formed througha wall of the box B, andZ asimilar orifice through the opposite side of the box, which two orificesare opposite each other and the bore of the lens-tube 9, so that a rightline or ray of light, 1 passing through the centers of said orifices kand Z would coincide with the axis of the lens-tube and be parallel withthe sides and base of the instrument. The eyeglass or lens I, the focaldistance of which is to be measured, is placed in a vertical positionflat againstthe outer end-of the lens-tube in the space It, as shown inFigs. 2 and 6, the axis of the lens being made to coincide with thecenter line, 1', above mentioned, the same being the axis of theinstrument. The cross wire a is held by a bent standard, 12, within theobject-box B, in position to cross horizontally and diametrically theorifice k, which standard is rigidly secured to a block or base, I),resting upon the base A of the instrument. A longitudinal screw, d,resting at its outer end in a wall of the box B, under the orifice 70,and at its inner end in a support,p, secured to the base A, passesthrough and is threaded in the block b, by means of which screw thecrosswire or object may be longitudinally adjusted. A lens, 6, is heldwithin the box B, opposite the orificel thereof, in a slide, 0, restingbetween ways 0, secured to the inner face of the wall of the box, so asto be moved laterally along the same. A rod, 1", connected with theslide 0, passes out through the wall of the box, terminating ina handle,25, by means of which the operator may withdraw the lens from theorifice Z or place it opposite the latter, at pleasure, a stop, 8,serving to limit the motion of the slide in an inward direction. Thelens tubeg is formed with a ring or head, u, let into the thick end 0 ofthe scale-box,

" said tube being also formed with a longitudinal slot, on. A circularslide, 1', for holding a lens, a, is fitted adj ustably to the interiorof the tube 9, and formed with a part, 2), reaching out through the slot0:, as shown, which part 9 is longitudinally bored and threaded outsideof the tube to receive a traverse screw, it, by means of which said lensmay be longitudinally adjusted within the tube. The head 6 of the screwit is squared to receive a wrench, and sunk into the ring a of the tube,to be out of the way of a lens, I, when placed against the tube, asabove stated, and the head 0 of the screw 61 is likewise squared andsunk into the walls of the box B. The slide L is formed of a frame, I),which frame supports in front a vertical disk of glass, d, ground uponits outer or front surface, also a mirror, f, inclined at an angle offorty-five degrees to the axis of the instrument. Just above the slideLthe scaleplate F rests within the box 0, the slide being permitted tomove longitudinally within said box under the scale. The scale is formedwith a central longitudinal slot, 9, and transverse graduation-marks 1are carved on either side of said slot, each of which is designated by anumber,,the orders of the two series of numbers being reversed, theupper series "being used in measuring the focal distance of a couvexlens, and the lower series, as appearing in Fig. 1, being used inmeasuring a concave lens. The frame 12 of the slide is provided with anindex, n, for the scale pointed in both directions, used to indicate theposition of the vertical object-glass d with reference to the scale,which indicates the scale-distance of said object-glass from the lensbeing measured. The index is placed directly over the object-glass.

WVhen the lenses are all properly adjusted, and the object-glass broughtto the focal point within the scale-box of the eyeglass or lens beingmeasured, the image of the object awill be clearly produced upon theground surface of the object-glass, as shown at a in Fig. 8, which imagewill be reflected by the inclined mirror f up through the slot 9 of thescale onto the long mirror K, as shown at a in Fig. 2, appearingtransversely thereupon. In practic after the lens to be measured is putin place, as above explained, the operator moves the slide Llongitudinally within the scale-box until a position is found at which adistinct image of the object a appears on the long mirror K, whichproves to him that the ground surface of the vertical objectglass isexactly at the focal point of said lens. WVhen the image appears thusWell defined upon the mirror K, the reading of the scale as determinedby the index gives the number of the lens. In use the device is placedwith the end P directed toward a window or other point of strong light,and in order that the image may appear clear upon the mirror K it isnecessary to exclude as much light as possible from the interior of thescale-box and from the obj ectglass and mirror f, excepting what passesThis screen expands in convenient reach of the operator. This slide isdesigned to be moved longitudinally within the 802115130X, on account ofwhich it is necessary to have a slit formed in the side of the box toaccommodate the handle in its various horizontal movements. To preventlight entering the scale-box through the slit for the handle, I form thefront side of the box of two strips or pieces, Zp, placing the formerabove and outside the latter and in position to partially overlap thesame, as shown in Fig. 8. These strips are placed slightly apart to forman opening or slit, 0', (Figs. 1 and 2,) through which to pass thehandle f, said handle being bent, as shown in Fig. 8, for the purpose.By this means a free motion of the slide and handle is permitted, whilethe light is not permitted to enter the box through the slit.

The adj ustability of the object a and lens a, above described, isimportant, for it enables the Optician to use scales in the instrumentthat are not exact copies of each other. If, for instance, the scale ofthe instrument become destroyed, and replaced by a new one slightlydifferently spaced, the readings thereon would be incorrect, and lensestested with the instrument could not be accurately numbered. Byadjusting the lens a and object a the instrument may be adapted toscales that slightly differ in make, causing the readings upon the sameto be eorrectthat is to say, to adapt a new and slightly-different scaleto the instrument, a lens, I, of some known numberas, for instanec,48isemployed. Should the index not indicate 48 upon the scale when the slideL is adjusted to throw a well-defined figure of the object a upon themirror K, then by adjusting the lens a the location of the focus of thelens I may be changed at will. This will cause the image of the objectto dis tinctly appear upon the long mirror when the slide is moved to aposition at which the index points to the division-mark numbered 48. Aslight movement of the lens a toward or from the lens I will require anincreased movement of the slide L in a corresponding direction to causea distinct image of the object to appear upon the mirror K. The sameeffect is produced by moving the object (a nearer to or farther from theorifice k. The adjustment of both the lens and object may be necessary,as either one alone may not prove sufficient to make the correctionnecessitated by the difference in the scales without moving it to an extreme position, which may be objectionable.

After the lens a and object a are adjusted to suit any given scale, theyare then not further disturbed, unless a new scale is to be fitted tothe instrument.

What I claim as my invention is 1. The box B of an instrument formeasuring the focal distances of optical lenses, formed with opposingopenings through opposite sides thereof, and provided with a lens, 0,and an object, a, longitudinally adjustable therein, in combination withthe scale-box O, joined to the box B, and formed with an openingopposite said openings in the box B, and provided with an adjustablelens, a, and slide L, substantially as described.

2. In combination with the scalebox C of an instrument for the focalmeasurement of optical lenses, provided with a tilting cover, D, andscale F, a slide, L, provided with an object-glass, d, inclined mirrorf, an index, a, the cover D, having a reflecting-mirror, K, upon itsinner surface, substantially as and for the purpose specified.

3. In combination with the sealebox G of an instrument for the focalmeasurement of optical lenses, provided wit-l1 a tilting cover, D, andscale F, a slide, L, within the scaleboX,provided with an object-glass,d, inclined mirrorf, an index, n, the cover D having areflecting-mirror, K, upon its inner surface, said slide being providedwith a handle, f, reaching to the exterior of the scale-box, and fittedto move longitudinally within the latter, substantially as described.

4. The combination, in an instrument for the focal measurement ofoptical lenses, of the scalebox 0, provided with a tilting cover, D, andmirror K, a scale, F, and slide L, within the scale-box, said slidebeing provided with an object-glass, d, inclined mirror f, an index, n,the scale-box being formed with an orifice, h, and provided with alens-tube, g, inserted therein, and an adjustable slide, 1', for holdinga.lens, a, fitted within the lenstube, with means, substantially asshown, to adjust said lens-slide within the tube, substantially as andfor the purpose set forth.

5. In combination with the scale-box C of an instrument for the focalmeasurement of optical lenses, a lenstube, 9, formed with a head orband, 11., and longitudinal slot an, a lens-slide, i7, fitted adjustablywithin the lenstube, said slide being formed with a part, c, reachingout through the slot 00, and an adjusting-serewfitted to the part c,substantially as shown and described.

6. In combination with the object-box B of an instrument for the focalmeasurement of optical lenses, formed with orifices 7c and Z. anadjustable cross-wire or object, a, held within the box by a standard,a, in position to cross centrally the orifice k, a block, b, for holdingthe standard it, and longitudinal adjustingscrew d, fitted to the blockb, to move the cr0ss-wire or object a toward or from the orifice k,substantially as shown and described.

7. The scale'box G of an instrument for the focal measurement of opticallenses, having one side thereof formed with the overlapping parts Z andp, with a space, 0, between them, in combination with a slide, L, forthe mirror and object-glass, fitted to move longitudinally within thescale-box, and bent han- IIC dle f, for the slide occupying said space0, glass, mirror, and index n, for the scale, and and reaching to theoutside of said scale-box, a screen, G, for the light, substantially asto substantially as and for the purpose specified. shown.

8. The combination, in an instrument for FREDERIO SOHARPR 5 the focalmeasurementof optical lenses, of the scale-box 0, provided with atilting cover, Witnesses: D, minor K, and scale F, and a slide, L, E. B.WHITMORE, within the scale box for holding the object- J. L. REYNOLDS.

